In the medical field it is becoming more and more common practice to use stereo microscopes for assisting medical professionals in performing such tasks as medical surgeries, examinations, treatments and the like. The medical professional using a conventional stereo microscope has to look through the eye-pieces thereof in order to study a region of interest. This, however, is often very inconvenient, because of the awkward positions the medical professional has to place himself in, in order to be able to look through the eye-pieces of the stereo microscope and to work with his hands within the region of interest. Obviously, such a situation is rather dissatisfying for the medical professional or the patient being examined and/or treated.
The position of the stereo basis of a stereo microscope is of major importance for displaying the stereo image on a display unit as well for actions of the medical professional which are triggered by what the medical professional perceives on the display unit. However, conventional stereo microscopes with a fixed stereo base have the problem that a change of the position of the microscope can lead to a rotation of the image and even to the image being displayed upside down. Obviously, this leads to an exchange of the two stereo channels on the display unit. The medical professional, i.e. the viewer, will perceive such rotations and/or exchanges in that an actual heightening is displayed as a depression and vice versa. Again, such a situation is rather confusing and, consequently, dissatisfying for the medical professional using a conventional stereo microscope.
Dentists often have to examine remote parts of the dental region of a patient which sometimes can be visually accessed only by means of a hand mirror. Consequently, such mirrors are still important even in case a stereo microscope is employed. However, using a mirror in combination with a stereo microscope involves additional challenges in that any light coming from the parts of the dental region of a patient being examined with a mirror will experience one additional interaction with the mirror (i.e. a reflection) before entering the stereo microscope. Conventional stereo microscopes do not have any means for compensating for such an effect.
The size of the field of view of a stereo microscope depends among other factors on the chosen magnification. For instance, in a zoom system with a ratio of 4:1 the diameter of the field of view would change e.g. from 100 mm to 25 mm. In conventional stereo microscopes the region illuminated by the internal lighting of the stereo microscope is fixed. This has the consequence that in conventional stereo microscopes only for a special setting the actual field of view coincides with the area illuminated by the internal lighting of the microscope. For any other setting the field of view and the area illuminated by the internal lighting of the microscope do not match such that either only a part of the actual field of view gets illuminated or that the area illuminated by the internal lighting of the microscope is larger than the actual field of view. In the latter case only a small part of the light emitted by the internal lighting of the microscope is actually “used”, whereas the bulk thereof is being wasted.
In conventional stereo microscopes the focus distance is changed at a constant rate. This has the consequence that at low magnifications the change of the focus is perceived to be rather slow, whereas at high magnifications the change of the focus is perceived to be rather fast. This, in turn, leads to a difficult, if not impossible fine adjustment of the focus distance at high magnifications in conventional stereo microscopes.
The internal lighting of a conventional stereo microscope generally illuminates the field of view thereof in a fixed angular relationship with respect to the optical axis of the stereo microscope. However, as already outlined further above, a medical professional and especially a dentist often will need to examine regions which are difficult to illuminate and, thus, to image by conventional stereo microscopes having a fixed internal lighting. Obviously, this situation is dissatisfying for the medical professional.
Microscopes employed in the medical field are often used together with an external light source each being mounted to a separate support system. The separate support systems of the microscope and the external light source are prone to colliding and interfering with each other and, consequently, it is often very difficult to manipulate and adjust these separate elements for providing an optimal internal and external illumination. Again, such a situation is rather dissatisfying for the medical professional using a conventional microscope together with an external light source.
The object of the present invention is to provide a stereo video microscope system overcoming or at least mitigating the problems associated with conventional systems as outlined above.